Compact folded dipole antenna with multiple frequency bands

Abstract

An antenna includes a first folded dipole, and a second folded dipole connected in parallel to the first folded dipole. The antenna further includes a conductor that extends across a first gap in the first folded dipole and a second gap in the second folded dipole to connect to a first central section of the first folded dipole and to a second central section of the second folded dipole.

What is claimed is: 
     
       1. An antenna, comprising:
 a first folded dipole; 
 a second folded dipole connected in parallel to the first folded dipole; and 
 a conductor that extends across a first gap in the first folded dipole and a second gap in the second folded dipole to couple to a first central section of the first folded dipole and to a second central section of the second folded dipole. 
 
     
     
       2. The antenna of  claim 1 , wherein a length of the conductor determines a primary frequency of the antenna. 
     
     
       3. The antenna of  claim 1 , wherein a first end of the conductor couples to a first dipole stub of the first folded dipole and a second end of the conductor couples to a second dipole stub of the second folded dipole. 
     
     
       4. The antenna of  claim 3 , further comprising:
 a planar dielectric, wherein the first folded dipole and the second folded dipole are formed on a first side of the planar dielectric and wherein the conductor is formed on a second side of the planar dielectric. 
 
     
     
       5. The antenna of  claim 4 , wherein the first end of the conductor capacitively couples to the first dipole stub across the planar dielectric and wherein the second end of the conductor capacitively couples to the second dipole stub across the planar dielectric. 
     
     
       6. The antenna of  claim 1 , wherein the first folded dipole includes a first feed arm and a first non-feed arm, wherein the first non-feed arm includes the first central section, and wherein a first dipole stub connects to the central section of the first non-feed arm, and
 wherein the second folded dipole includes a second feed arm and a second non-feed arm, wherein the second non-feed arm includes the second central section, and wherein a second dipole stub connects to the central section of the second non-feed arm. 
 
     
     
       7. The antenna of  claim 4 , further comprising:
 a feed conductor line, formed on the second side of the planar dielectric, that connects to a feed section of the first and second folded dipoles. 
 
     
     
       8. The antenna of  claim 7 , further comprising:
 an impedance matching element formed at a location along a length of the feed conductor line. 
 
     
     
       9. The antenna of  claim 4  further comprising:
 an impedance matching element, formed on the second side of the planar dielectric, that electrically couples to a feed section of the first and second folded dipoles. 
 
     
     
       10. The antenna of  claim 1 , further comprising:
 a third folded dipole formed within the first folded dipole and a fourth dipole formed within the second folded dipole due to the conductor coupling to the central section of the first folded dipole and to the central section of the second folded dipole. 
 
     
     
       11. An antenna structure, comprising:
 a planar dielectric; 
 a conductor layout formed on a dielectric, wherein the conductor layout forms a first folded dipole coupled in parallel to a second folded dipole; 
 a feed line conductor formed on the dielectric; 
 a first conductor, formed on the dielectric, that couples to the first folded dipole at a first end of the first conductor and to the second folded dipole at a second end of the first conductor; and 
 a second conductor formed on the dielectric across a first gap between the first folded dipole and the second folded dipole. 
 
     
     
       12. The antenna structure of  claim 11 , wherein the second conductor comprises an impedance matching element for the antenna structure. 
     
     
       13. The antenna structure of  claim 11 , wherein the dielectric comprises a planar dielectric, wherein the conductor layout is formed on a first side of the planar dielectric, and wherein the feedline conductor, the first conductor, and the second conductor are formed on a second side of the planar dielectric that is opposite to the first side. 
     
     
       14. The antenna structure of  claim 11 , wherein a length of the first conductor determines a primary frequency of the antenna structure. 
     
     
       15. The antenna structure of  claim 11 , wherein the first conductor extends across a second gap in the first folded dipole and a third gap in the second folded dipole to couple across a first central section of the first folded dipole and a second central section of the second folded dipole. 
     
     
       16. The antenna structure of  claim 15 , further comprising:
 a third folded dipole formed within the first folded dipole and a fourth folded dipole formed within the second folded dipole due to the first conductor connecting across the central section of the first folded dipole and the central section of the second folded dipole. 
 
     
     
       17. The antenna structure of  claim 11 , further comprising:
 a third conductor formed at a location along a length of the feed line conductor. 
 
     
     
       18. The antenna structure of  claim 17 , wherein the third conductor comprises an impedance matching element of the antenna structure. 
     
     
       19. The antenna structure of  claim 11 , wherein the first folded dipole includes a first dipole stub and the second folded dipole includes a second dipole stub, and wherein the first end of the first conductor couples to the first dipole stub and the second end of the first conductor couples to the second dipole stub. 
     
     
       20. An antenna structure included in a utility meter, comprising:
 a planar dielectric; 
 a conductor layout formed on a first side of the planar dielectric, wherein the conductor layout forms a first folded dipole connected in parallel to a second folded dipole; 
 a feed line conductor formed on a second side of the planar dielectric, opposite to the first side; 
 a first impedance matching conductor formed on the second side of the planar dielectric; and 
 a first frequency tuning conductor formed on the second side of the planar dielectric, 
 wherein the first folded dipole includes a first dipole stub and the second folded dipole includes a second dipole stub, and wherein a first end of the first frequency tuning conductor capacitively couples to the first dipole stub through the planar dielectric and a second end of the first frequency tuning conductor capacitively couples to the second dipole stub through the planar dielectric.